A power unit converter is essential when comparing engines rated in horsepower to electric motors rated in kilowatts, or when sizing HVAC equipment in BTU/hr vs kW. Enter any value in any power unit to see all equivalents instantly.
Power Unit Converter
Common Power References
| Application | Typical Power |
|---|---|
| LED light bulb | 10 W |
| Electric kettle | 1.5–3 kW |
| 1-ton AC (cooling) | 12,000 BTU/hr |
| Car engine (average) | 150–300 hp |
| Router motor | 1.75–3 hp |
| Nuclear power plant | 1,000 MW |
How to Convert Power Units
Power is the rate of energy transfer — how fast work is done or energy is used. The SI base unit is the watt (W), where 1 watt = 1 joule per second. Different industries use different units: mechanical engineers prefer horsepower (hp), HVAC engineers use BTU/hr, and European vehicle specs use kilowatts (kW) or metric horsepower (PS).
Motor and Engine Ratings
American engines and motors are typically rated in mechanical horsepower (1 hp = 745.7 W). European and Japanese vehicle specs use kW or PS (metric hp, 1 PS = 735.5 W). Electric motors are sometimes rated in electrical horsepower (1 hp = 746 W exactly). When comparing motors across systems, convert everything to watts or kilowatts for a clean comparison.
HVAC and Heating Sizing
HVAC systems in the United States are rated in BTU/hr (British Thermal Units per hour) and "tons" (1 ton = 12,000 BTU/hr = 3.517 kW). Gas appliances are rated in BTU/hr; electric appliances in kW. To compare: 1 kW = 3,412 BTU/hr. A 100,000 BTU/hr gas furnace = 29.3 kW of heating capacity.
Quick Conversion Reference
The most commonly needed conversions: 1 kW = 1.341 hp (mechanical); 1 hp = 0.7457 kW; 1 kW = 3,412 BTU/hr; 1 BTU/hr = 0.293 W; 1 ton (cooling) = 3.517 kW = 12,000 BTU/hr. For electric motor sizing in the US, power is often specified as horsepower but purchased as kilowatt-hour electricity — always convert to kW to calculate operating costs.
Frequently Asked Questions
How many watts is 1 horsepower?
1 mechanical horsepower (HP) = 745.7 watts. 1 electrical horsepower = 746 watts exactly. 1 metric horsepower (PS) = 735.5 watts. The mechanical horsepower is the most common in the United States for engines and motors. The small difference between mechanical and electrical HP rarely matters in practice.
How do I convert kilowatts to BTU per hour?
Multiply kilowatts by 3,412.14 to get BTU/hr. For example, a 5 kW electric heater produces 5 × 3,412.14 = 17,061 BTU/hr. This conversion is commonly needed for HVAC sizing, comparing gas and electric appliances, and calculating heating system output. 1 ton of air conditioning = 12,000 BTU/hr = 3.517 kW.
What is the difference between mechanical and electrical horsepower?
Mechanical horsepower (hp) = 33,000 ft·lbf/min = 745.69987 watts, used for engines, vehicles, and equipment. Electrical horsepower = 746 watts exactly, used for electric motors. Metric horsepower (PS or CV) = 75 kgf·m/s = 735.49875 watts, used in Europe and Japan for vehicle ratings. The differences are small but matter for precise calculations.
How many watts is 1 ton of air conditioning?
1 ton of cooling = 12,000 BTU/hr = 3,516.85 watts (3.517 kW). This comes from the heat required to melt one ton of ice in 24 hours. A 2-ton AC unit produces 24,000 BTU/hr = 7,034 watts of cooling. Note: the 'ton' rating refers to cooling capacity, not the electrical power the unit consumes.
Is this power unit converter free?
Yes, completely free with no signup required. All conversions run instantly in your browser.